The present invention relates to a marine vessel corrosion control system. In the prior art, it is well known that metallic parts of a marine vessel submerged underwater are susceptible to corrosion through the process known as electrolysis. Galvanic corrosion is typically a slow process, however, over a lengthy period of time, it can result in deterioration of underwater metallic parts and in endangerment of the watertight integrity of a boat hull. Those of ordinary skill in the art realize that galvanic corrosion promotes deterioration and failure of underwater parts made of alloys of bronze. Left unprotected, such alloys waste away resulting in failure of component parts.
Under circumstances where stray currents arise from current leakage from a vessel as well as from external power sources, galvanic corrosion can be much more rapid and catastrophic.
For many years, boat manufacturers have included in the boats they manufacture numerous pieces of a sacrificial anode material such as pure zinc or an alloy of aluminum fastened to parts that might be subject to galvanic corrosion, with these anodes electrically connected together using heavy gauge conductors connected to the vessel's electrical ground. Such a system facilitates deterioration of the sacrificial anodes rather than of the component parts to which they are attached. Other systems have been devised to control galvanic corrosion including the use of a source of electrical current supplied to anodes attached to the component parts of the vessel that are to be protected. Such systems can be effective but, if they fail, for any reason, the boat owner is left with a completely unprotected vessel in which the submerged metallic component parts are immediately subject to galvanic corrosion.
As such, a need has developed for a system for protecting a marine vessel against the effects of galvanic corrosion that includes a back-up system that is effective when the primary system is rendered inoperative for any reason.
Applicants are aware of the following U.S. patents:
2,402,494 to Hantzsch et al.3,004,905 to Sabins3,055,813 to Schaschl et al.3,098,026 to Anderson3,129,154 to Fry3,208,925 to Hutchison et al.4,136,309 to Galberth4,510,030 to Miyashita5,139,634 to Carpenter5,627,414 to Brown et al.
Each of the above-listed references teaches a system for protecting a vessel or structure against the effects of galvanic corrosion. Carpenter teaches such a device including selective use of an impressed or sacrificial protection anode assembly for a well. None of the other patents teaches breaking a connection of a sacrificial zinc anode using an energized magnetic coil or digital switch. The present invention differs from the teachings of these patents alone or in combination as contemplating a passive system for protecting the metallic component parts of a marine vessel from the effects of galvanic corrosion in combination with an active galvanic corrosion prevention system that impresses a desired electrical current on the submerged metallic component parts. The system of the present invention differs from the teachings of these patents as including a switching system that senses when the active system is inoperative and switches the passive zincs into connection with the submerged metallic components to maintain protection until such time as the active system may be repaired and placed back into operation.